Tools capable of providing accurate, non-invasive, and quantitative structural and blood flow measurement of body parts in vivo are highly desirable in applications such as medical diagnosis and therapeutic progress monitoring. In this respect, optical coherence tomography (OCT) has been seen as a promising technology for providing such a capability.
Optical coherence tomography [1] is a recently developed technology that is capable of providing high-resolution cross-sectional imaging and is commonly used in the diagnosis and management of retinal diseases [2-4] and glaucoma [5, 6]. In addition to obtaining morphological images, OCT can also detect a Doppler shift of reflected light, which provides information on flow and movement [7-9]. Several investigators have studied the visualization of blood flow and flow dynamics using Doppler OCT [10-14]. The availability of Fourier Domain OCT allows the measurement of the Doppler shift, but this information alone only correlates to the blood flow in the direction of the scanning beam. Blood movement in the direction perpendicular to the scanning beam is not directly reflected in the Doppler shift. Thus, in order to measure volumetric flow, one must also know the incident angle between the scanning beam and the direction of the blood flow. This information cannot be obtained from a single cross-sectional OCT image, hence, volumetric flow measurement by Doppler OCT was hitherto not possible.
Therefore, there still exists a need for methods and tools that can overcome the problems in the art to provide practical, efficient, fast, sensitive, non-invasive and accurate measurements of in vivo blood flow.